:root {
  --canvas: #ffffff;
  --canvas-subtle: #f6f8fa;
  --fg: #24292f;
  --fg-muted: #57606a;
  --fg-subtle: #6e7781;
  --border: #d0d7de;
  --border-muted: #eaeef2;
  --accent: #0969da;
  --warning: #9a6700;
  --warning-subtle: #fff8c5;
  --warning-border: #d4a72c66;
  --shadow-sm: 0 1px 3px rgba(27, 31, 36, 0.04);
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans", Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
  --measure: 42rem;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
}

body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  background: var(--canvas);
  color: var(--fg);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

html[data-lang="zh"] .en,
html[data-lang="en"] .zh {
  display: none;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.skip {
  position: absolute;
  left: 1rem;
  top: -4rem;
  z-index: 20;
  padding: 0.5rem 0.75rem;
  border-radius: 6px;
  background: var(--fg);
  color: #fff;
}

.skip:focus {
  top: 0.75rem;
}

.lang-switch button:focus-visible,
a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.banner {
  background: var(--warning-subtle);
  color: var(--warning);
  border-bottom: 1px solid var(--warning-border);
}

.banner p {
  margin: 0;
  padding: 0.7rem 0;
  font-size: 0.9rem;
  font-weight: 650;
}

.container {
  width: min(1040px, calc(100% - 2rem));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  gap: 1rem 1.25rem;
  min-height: 64px;
  flex-wrap: wrap;
  padding: 0.5rem 0;
}

.wordmark {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--fg);
  font-weight: 650;
  letter-spacing: -0.02em;
  text-decoration: none;
}

.wordmark img {
  display: block;
  width: 22px;
  height: 22px;
}

.wordmark:hover {
  color: var(--fg);
  text-decoration: none;
}

.header-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
  margin-left: auto;
}

.header-links a {
  color: var(--fg-muted);
  font-size: 0.875rem;
  font-weight: 550;
  text-decoration: none;
}

.header-links a:hover {
  color: var(--fg);
  text-decoration: none;
}

.lang-switch {
  display: inline-flex;
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
  background: var(--canvas-subtle);
}

.lang-switch button {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--fg-muted);
  font: inherit;
  font-size: 0.8rem;
  font-weight: 650;
  min-height: 32px;
  padding: 0 0.7rem;
  cursor: pointer;
}

.lang-switch button[aria-pressed="true"] {
  background: var(--canvas);
  color: var(--fg);
  box-shadow: inset 0 0 0 1px #24292f;
}

main {
  flex: 1;
}

.hero {
  padding: 4.5rem 0 5rem;
}

.eyebrow {
  margin: 0 0 0.75rem;
  color: var(--fg-subtle);
  font-size: 0.8rem;
  font-weight: 650;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

h1 {
  margin: 0 0 0.75rem;
  font-size: clamp(2.1rem, 4vw, 2.75rem);
  line-height: 1.15;
  letter-spacing: -0.03em;
  font-weight: 650;
}

.lede {
  max-width: var(--measure);
  margin: 0;
  color: var(--fg-muted);
  font-size: 1.125rem;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.75rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 40px;
  padding: 0.35rem 0.95rem;
  border-radius: 6px;
  font-size: 0.95rem;
  font-weight: 650;
  box-shadow: var(--shadow-sm);
  text-decoration: none;
}

.btn:hover {
  text-decoration: none;
}

.btn-primary {
  border: 1px solid #18181b;
  background: #18181b;
  color: #fff;
}

.btn-primary:hover {
  background: #27272a;
  color: #fff;
}

.btn-secondary {
  border: 1px solid var(--border);
  background: var(--canvas);
  color: var(--fg);
}

.btn-secondary:hover {
  background: var(--canvas-subtle);
  color: var(--fg);
}

footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem 0 2.5rem;
  color: var(--fg-subtle);
  font-size: 0.875rem;
}

.footer-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.75rem 1.5rem;
}

.footer-brand,
.footer-note {
  margin: 0;
}

.footer-brand {
  color: var(--fg);
  font-weight: 650;
}

@media (max-width: 640px) {
  .header-links {
    margin-left: 0;
  }

  .lang-switch {
    margin-left: auto;
  }

  .hero {
    padding-top: 2.5rem;
    padding-bottom: 3.5rem;
  }
}